Saturday, June 25, 2011

The Brain Is Not Made Of Soup

Here's an article summarizing the original piece. The author's the head of a British think tank, but not a specialist in mental health, so he's probably a good example of the ''intelligent layman":

Neither – in relation to the fastest rising [mental health] diagnoses – is there any evidence of chemical imbalances in the brains of patients. In other words, the problem the [psychiatric] drugs are supposed to solve is an illusion.

There's no evidence of fairies in my garden, either. The concept of a 'chemical imbalance' in the human brain is one of the most fantastic oversimplifications in science, and one of the worst legacies of the modern pharmaceutical industry.

A bowl of soup could have a chemical imbalance. If you're making a chicken broth and you accidentally put in an extra spoonful of coriander, it'll taste horrible. Not enough salt, and it'll be bland. A soup is simple: too much or too little of one thing, and it comes out wrong.

Or...does it? Actually, flavour isn't just the sum of the ingredients. You might put in some extra coriander, and also put in some chilli powder, and that would end up delicious whereas if you left the coriander the same, it would be overwhelmed by the chilli. But you'll need to rethink the paprika as well...

Soups are pretty complicated.

The brain is a restaurant with a hundred billion tables. At each table sits a food critic. An army of chefs prepares an infinity of soups - no two are the same, although some areas of the restaurant tend to get certain kinds - and a legion of waiters serves them up, collects the old bowls and takes them to the kitchen to be washed and refilled.

Each critic has his own preferences. If she gets the right soup, she'll be happy. One soup will be great for one critic, disgusting to another. Some critics demand an ever-changing series of courses, others want the same thing day in day out.

Whether the restaurant gets a good review will depend on the composition of the soups, of course, but on so much else as well: are they delivered on time? Do the waiters collect the empty bowls quickly enough - or do they do it too fast, snatching soup away before it's been eaten? Who are the critics, anyhow?

This is still far too simple. In fact, the waiters and the chefs and the dishwashers are the critics, and how they do their job depends on what soup they're getting. That depends on how they've done their jobs in the past... and everyone's also a musician, playing their part in a symphony that we can't hear and couldn't begin to understand if we did.

Our technology for investigating the chemistry of the brain is comically crude. We can't eventake a sample of all of the soups in the whole restaurant, mix them all up and measure their average ingredients. You can do that in animals, but for ethical reasons, not in humans. No-one has ever measured the chemical composition of a living human brain.

We can sneak into the kitchen and chuck some spice into the pots, to see what kind of noise the critics make. We can't hear what they're saying, we can only measure the volume from different parts of the restaurant. Some of the most informative studies come from measuring the composition of the waste that gets thrown out in the bins every night.

So next time someone confidently tells you that mental illness either is, or isn't, a chemical imbalance, ask them - which one?